Multiple-hearth electric furnace.



A. HELFENSTEIN. MULTIPLE HEABTH ELECTRIC FUFNACE.

APPLICATION FILED JUNE 5,191

Patented Apr. 17, 1917.

2 SHEETS-SHEET I.

A. HELFENSTEIN. MULTIPLE HEARTH ELECTRIC FURNACE.

APPLICATION FILED JUNE 5, m4.

1,223,278. Puflmtod Apr. 17, 1917.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

ALOIS HELFENS'IEIN, OF VIENNA, AUSTRIA, ASSIGNOB TD UNION CARBIDE COMPANY, A CORPORATION 01 VIRGINIA.

Specification of Letters Patent.

Patented Apr. 17, 1917.

Application filed June 5, 1914. Serial No. 343,244.

1 To all whom it-may 001mm:

Be it known that I, ALOIs HELrENs'rEIN, a citizen of Switzerland, and a resident of Vienna, Austria, have invented an Improved and Novel Multiple-Hearth Electric Furnace, of which the following is a specification.

Itis known in multiple-hearth electric furnaces of the before-mentioned kind to arrange a charging bell'or shaft around every! electrode in order to effect a continuous charging operation around the same, and to draw off from said hell or shaft the furnace gases, or, if the furnace is closed, to force said gases to collect below the furnace roof in order to be either burnt in the furnace or to be conducted away.

Especiallyin furnaces intended for large outputs and having consequently a large consumption of raw materials, those arrangements entail complicated constructions, the superintendence arid maintenanceof which necessitate, in their turn, interruptions of work; Moreover, they require generally special arrangements for packing the place where .the electrode enters the bell, because an easy and good regulation of the electrodes is one of the chief conditions to be fulfilled in high-power plants. Furthermore, broken electrodes can be removed from such bells but with 'difiiculty, and exchanging the electrodes necessitates, with a closed bell, a great expense of time. Ghiefly, however, the bell and hopper arrangements in question do not answer the requirements if large quantities of mixed materlalsare to be treated, the difficulty being that, in highpower plants, the consumed quantities of mixture cannot be replaced quickly enough. Finally, the bells and hoppers consist partly of iron and other metals; this fact however has an unfavorable influence upon theelectrio relations, especially the phase-displacement, because leakages of current from the electrodes to those iron or metallic parts frequently occur.

Theobject of the present invention is to do away with the before-mentioned drawbacks and to allow of an ample charging of the furnace, in connection with an ample, practically complete, drawing off of the furnace gases, obviating at the same time comhopper may be formed by an upward extension of sa d furnace shaft proper. The electrodes are then lodged, during the operation, comple tely within the mixture, for a length of 1.5- 2.5 meters, as the case may be, and this colur in of mixture serves as a pack- 'ing for those electrodes. Charging the common shaft is very easy, and may be effected in a continuous and mechanical way, and very few operators are required for it.

In order to obtain the gases develo ing during the process in a simple as we l as reliable and safe manner, gas outlet pipes, preferably provided withwater jackets, are introduced around the electrodes through the side walls of the charging shaft into this latter, or tubes or bells are introduced from above th rough the charging shaft down into the charge farenough .to let the material lying over the lateral apertures or tube openings form a natural packingpreventing the access of fresh air from above. There may be a plurality of such gas conduits or exit openings in the side walls of the charg ing shaft, just as required, without render ing the furnzce complicated or preventing roper and annle charging thereof. During the operat on attention is paid to whether or not small g ts flames appear upon the mixture, or upon the chargln material respec tively, such flames indicating that thegas is not completely drawn oil through the described conduits or openings, and conse quently a certain small over-pressure exists in the furnace Thismay be regulated easily and efi'ec;ively by means of throttlevalves provided in said gas conduits, asis all more fully described hereinafter.

The height of the charging shaft 'exten sion depends, of course, upon the process, especially, however, upon whether or not pulverulent o:' granulated material is made use of. At an y rate, the height of the charging shaft is so determined that the furnace .gases cool down-as far .as possible in the charge itself 71. e. before they arrive at the exit opening, the purpose being to let the gases give off to the mixture their heat and eventually their reduction power.

The height should also be such as is necessary for packing the openings of the gas outlet conduits, and further to allow a certain length necessary for some spare material, according to the manner of charging the charging shaft. If, for instance, iron ores are to be reduced, an electrode of 2 meters length will be completely covered by the charge and also the electrode socket will get down in course of time into the charge, as the electrode is, consumed during the course of the process. If, however, the height of the normal working shaft of an electric raw iron furnace amounts, for instance, to about 1.52 meters, the height of the charging 'shaft forming the extension of the former will amount to about 1.5-3 meters or even more.

In order to prevent as far as possible leakage of the current from the electrodes to the mixture surrounding them, the electrodes, as well as their sockets, are electrically insulated as perfectly as possible by means of a suitable insulating material consisting, for instance, of asbestos which may be stifl'ened or reinforced by a sheet-metal sleeve. The length of the combined insulating material and sleeve is so chosen that the electrode sockets are protected to a height of at. least 1 meter. The insulating material and the sleeve are rigidly connected with the electrode and are consumed with the latter in the furnace.

In order to prevent leakage of current from one electrode or electrode socket through the charge of the charging shaft to the next electrode, and to keep up service with the electrodes of the remaining phases if those of any one phase are to be exchanged, and to prevent air from finding access to the gas exit partition wa ls are inserted in the common charging shaft between the electrodes of different polarity, said walls extendin downwardly below said gas exit ipes. he said walls may be built up of e-bricks, forming vaulted girths extending from one wall of the furnace to the other.

In order to make my invention more clear, I refer to the accompanying drawing which shows the subject matter of the invention ap lied to a'three-phase furnace.

i re 1 is a longitudinal section through the mace, the plane of section being laid through the three electrodes and the parts being shown in the position they occupy during operation.

Fig. 2 1s a cross section through the same furnace, in the plane of one Bundle of the electrodes;and'

Fig. 3 is a similar section, showing a someipes of the working electrodes, I

what different arrangement of the means for drawing oil the gas.

a a a, are the three electrodes of different polarity, or the bundles of such electrodes respectively; b is the common reaction shaft and c a is the common char ing shaft, located just above the shaft The upper ends of the electrodes are provided with the sockets f, f 1, serving for attaching the conductors, and each electrode and its socket have a common insulating sleeve 9 .9, 9,. Between every two of the reaction hearths 18 arranged, in the charging shaft, a partition wall It, or k, respectivelyyextending preferably down into the reaction space and consisting each of, or forming each, a fireproof girth.

The as is drawn off either through tubes 2', i, (F ig. 1) inserted into the wall of the charging shaft and provided with water jackets (the regulation being effected by throttle valves d), or by means of tubes m m (Fig. 3) extending from above into the common charging shaft and having enlarged ends. The arrangement of these pipes may be suc'h'that a regulation with respect to the depth of entrance of the gases during operation is rendered possible, for instance, by means of a chain and a counterwei ht, as shown in Fig. 3.

T e collected gases pass over-into the conduits n, 12 which, according to the process, may serve also as combustion or as condensation pipes, or they may be constructed in such a manner that'the gases are conducted away through thesame'without being burnt, or t at they are burnt in the presence of or together with a suitable supply of air.

The before-described improved furnace is intended especially for the production of heavy metals, alloys having iron as a component and volatile metals and their oxids, such as zinc and oxid of zinc; also other electro-thermic reactions may be carried out with its aid.

Having now described my invention, what I desire to secure by Letters Patent of the United States is:

1. In a multiple-hearth electric furnace provided with vertical electrodes of different olarity arranged one over each smelting hearth, the combination,'with the reaction shaft of the furnace which is adapted to receive all electrodes of diflerent polarity, of a char 'ng shaft arranged over said reaction shag, and gas outlet pipes extending into the'm'aterial contained 1n said charging shaft down to a depth where the charging material above the pipe entrances is capable of serving as a packmg to prevent the access of fresh air, said electrodes extending through the said charging shaft, for the purpose as described.

2. In a multiple-hearth electric furnace provided with vertical electrodes of different polarity arranged one over each smelting hearth, the combination, with the reaction shaft of the furnace which is adapted to receive all electrodes of different polarity,

of a char ing shaft arranged over said reaction sha t, and gas outlet pipes reaching from above through the upper layer of the tion shaft of the furnace which is adapted to receive all electrodes of different polarity, of a char ing shaft arranged over said reaction shaft, and electrical insulators each inclosing an electrode bundle and its sockets, the length of each cover in upward direction being such as to prevent the charge from comingl in contact With the sockets, even when t e electrodes have been completely consumed. r

4. In a multiple-hearth electric furnace provided with vertical electrodes of different polarity arranged-one over each smelting hearth, the combination, with the reaction shaft of the furnace which is adapted to receive all electrodes of different polarity, of a charging shaft arranged over said reaction shaft, 'gas outlet conduits communicating with the interior of said charging shaft at a depth where the charging material above the entrance openings of said conduits will prevent the access of air, and electrical insulators inclosing each an electrode bundle and its sockets, the length of each cover in upward direction being such as to prevent the charge from coming in contact with the sockets, even when the electrodes have been completely consumed.

5. In a multiple-hearth electric furnace provided with vertical electrodes'of different polarity arranged one over each smeltinghearth, the combination, with the reaction shaft of the furnace which is adapted to receive all electrodes of different polarity, of a charging shaft arranged over said reaction shaft, partition; walls arranged each between two electrodes of different-epolarity and above the workin zone of said electrode, and electrical insuators each inclosing an electrode bundle and its sockets, the length of each cover in upward direction being such as to prevent the charge from coming in contact with the sockets, even when the electrodes have'been completely consumed.

6. In an electric furnace, a smeltingtrodes extending downward through the smelting-hearth, the

charging-shaft to said portions of said electrodes in the chargingshaft being electrically insulated withln the charge. c

7. In an electric furnace, a smeltin hearth, a charging-shaft thereover, and a justable electrodes extending downward through the chargin ;-shaft to said meltinghearth, the portions of said electro es in the charging-shaft being protected within the charge by electrica insulation consumable therewith. l

8. In an electric furnace, a smeltinghearth, a charging-shaft thereover, and adjustable electrodes extending downward through the chargin g-shaft to said smelting. hearth, the portions of said electrodes in the charging-shaft being protected within the charge by electrical insulation consisting of metal-reinforced asbestos.

9. In an electric" furnace, a smeltinghearth, a charging shaft thereover, adjustable electrodes extending downward through the charging-shaft to said smelting-hearth, electrode-holders movable with their electrodes through the charge, and casings for electrically insulating said electrodes and said holders for p1 otecting them within the charge, the insulition being consumable with the electrodes 1 10. In an elect: 'ic. furnace, a smeltinghearth, a chargingf-shaft thereover, adjustable electrodes extending downward through the charging-shaft to said smelting-hearth, electrode-holders movable with their electrodes through the charge, and casings for electrically insulafing said electrodes and said holders for p 'otecting them within the charge, said insulating casings comprising asbestos jackets with reinforcing metal sleeves.

11. In an electric furnace, at smeltinghearth, a chargi ag-shaft thereover, electrodes extending downward through the charging-shaft ti said smeltin -hearth, means extending into the charge or withdrawing the gases therefrom and means for controlling the eff ux of the gases.

12. In an electric furnace, a smeltinghearth, a charging-shaft thereover, else-- trodes extending downward through the charging-shaft to said smelting-hearth, and a gas oulet-pipe i1 said charging-shaft having its receiving -end in the body of the charge. a

13'. In an electric furnace, a smeltinghearth, a charg .ng-shaft thereover, electrodes extending downward through the charging-shaft tc said smelting-hearth, and. a gas outlet-pipe .nsaid charging-shaft having a flaring rec eiving-end in the body of the charge.

14. In an elettric furnace, a smelting- 65 hearth, a charging-shaft thereover, and elechearth, a charging-shaft thereover, clec- 130 trodes extending" downward through the In testimony whereof I aflix my signature charging-shaft to said smeltinghearth, a in presence of two witnesses.

gas outlet-pipe extending downwardly into ALOIS HELFENSTEIN. saidcharging-shaft having its receiving-end Witnesses: 5 in the body of the charge, and means for IGNAZ KNGPFELMACHEB,

adjusting the height of said receiving-end. AUeUsT Fveenn'. 

